Strong durable press cellulosic fabrics

ABSTRACT

TENSILE PROPERTIES AND ABRASION RESISTANCE OF DURABLE PRESS CELLULOSIC FABRICS ARE IMPROVED BY TREATMENT WITH CYCLIC ACETALS OBTAINED BY REACTION OF GLYOXAL WITH ETHYLENE GLYCOL. THE CYCLIC GLYOXAL ACETALS USUALLY ARE APPLIED TO THE FABRIC AS A MIXTURE OF TWO ISOMETRIC FORMS, AND THE TREATED FABRIC IS CURED IN THE PRESENCE OF THE DURABLE PRESS FORMULATION.

United States Patent Office Patented Oct. 10, 1972 ABSTRACT OF THE DISCLOSURE Tensile properties and abrasion resistance of durable press cellulosic fabrics are improved by treatment with cyclic acetals obtained by reaction of glyoxal with ethylene glycol. The cyclic glyoxal acetals usually are applied to the fabric as a mixture of two isomeric forms, and the treated fabric is cured in the presence of the durable press formulation.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a novel process for imparting to cellulosic durable press fabrics high tensile strength and abrasion resistance.

Prior art Durable press fabrics are well known in the art. They are usually prepared by impregnating the fabric with a resin, a resin-forming material, or a cellulose-crosslinking agent. Commonly used chemicals are dimethyloldihydroxyethyleneurea and methyl bis(hydroxymethyl) carbamate.

Thermosetting resins currently in use reduce the tensile strength and abrasion resistance of all-cotton fabrics, often by about 40-60% under normal treating conditions. At the present time, the most widely used method for improving the tensile strength of cellulosic durable press fabrics is to use a blend of all-cellulosic fibers, such as cotton, with non-cellulosic synthetic fibers, such as a polyester. Thus, the durable press qualities are obtained with the resin-treated cotton, and improved strength is obtained from the polyester.

Although blended, durable press fabrics have satisfactory tensile properties, their abrasion resistance is unsatisfactory. In a durable press blend, frosting and pilling are commonly encountered and detract from the appearance of the garment. The frosting and pilling are caused by the cellulosic fibers wearing out at a much higher rate than the synthetic fibers, with resulting shade changes at points of high wear (frosting) or the accumulation of detritus on the surface of the fabric (pilling).

There is a great need in the art for a process which would impart to durable press cellulosic fabrics good tensile properties and abrasion resistance.

Definition The term cellulosic fabric, as used herein, means a fabric either wholly constituted of cellulosic fibers or constituted of a blend of Cellulosic and noncellulosic fibers, either natural or synthetic. Cellulosic fibers include cotton, rayon, cellulose acetate, and linen. Noncellulosic fibers include both natural and synthetic fibers, e.g., silk, polyester, polyacrylonitrile, and polyamide fibers. A representative polyester fiber is poly(ethylene terephthalate), While representative polyamides are nylon 66 and nylon 6.

The term durable press fabric is used herein to mean a fabric having smooth-drying, crease-resisting properties.

SUMMARY OF THE INVENTION According to this invention, it has now been discovered that certain cyclic glyoxal acetals improve the tensile properties and abrasion resistance of durable press cellulosic fabrics. The glyoxal aceta-treated fabric is cured by heating in the presence of the durable press agent and a Lewis acid catalyst.

DETAILED DESCRIPTION OF THE INVENTION The glyoxal acetals utilized in the process of this invention are 2,2 bis-1,3-dioxolane (1) and p-dioxino [2,3-b]-p-dioxin (2).

O O O 0 o 0 0 0 While each one of the above two compounds could be employed by itself, usually a mixture of (l) and (2) is used. The relative proportions of these acetals are not critical. A mixture containing about 70% of (1) and 30% of (2) is obtained when glyoxal is allowed to react with ethylene glycol in an anhydrous medium in the presence of an acidic catalyst. Such a mixture is suitable in the process of the present invention.

Compounds l) and (2) have been reoprted by Sprung et al., J. Am. Chem. Soc., 73, 1884 (1951) and by Astle et al., Ind. & Eng. Chem, 46, 787 (1954). Both compounds are solids, soluble in water at 25 C. to the extent of about 3% or less. A mixture of (1) and (2) melts at about 105 C. For application to the fabric, the above glyoxal acetals are either dissolved in an organic solvent or emulsified in water.

Any organic solvent in which glyoxal acetals are soluble and stable, and which does not degrade the fabric, can be used. Suitable representative organic solvents include chlorinated aliphatic hydrocarbons such as trichloroethylene, perchloroethylene, and carbon tetrachloride; lower ketones such as acetone, methyl ethyl ketone, and cyclohexanone; lower ethers such as diethyl ether, dibutyl ether, tetrahydrofuran, and dioxane; lower alcohols such as methanol, ethanol, and isopropyl alcohol; esters such as ethyl acetate, butyl acetate, and ethyl propionate; and highly polar solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide. The preferred sol- 'vents are trichloroethylene and 1,1,1-trichloroethane.

Aqueous emulsions of glyoxal acetals can be prepared by methods generally known to the art. Glyoxal acetals thus are dissolved in a small volume of a water-immiscible solvent, such as a hydrocarbon, chlorinated hydrocarbon, ester, or ketone, and one or more surfactants or emulsifying agents are added to such concentrated solution. Suitable emulsifying agents include alkyl aryl polyethoxy alcohols, polyoxyethylene sorbitol or sorbitan fatty acid esters, fatty alkylolamide condensates, amine salts of fatty alcohol sulfates, petroleum sulfonates, etc. Concentrated glyoxal acetal solutions containing emulsifying agents can be readily dispersed in water, forming emulsions.

When a watenemulsifiable concentrate of the acetals is used, this concentrate can be added to a conventional durable press formulation such as Formulation I, described below, thus eliminating separate padding and drying steps. Alternatively, glyoxal acetals can be added to an emulsion of a durable press agent formulation in a chlorinated solvent such as trichloroethylene or 1,1,1-trichloroethane. An emulsion corresponding to Formula II, below, can be used advantageously. Finally, a durable press formulation can be emulsified in a solution of glyoxal acetals in a chlorinated solvent.

The concentration of glyoxal acetals in the solution or emulsion from which they are applied to fabric can be as low as 1 weight percent, based on the weight of the solution. However, concentrations of from 2 to weight percent will normally be preferred. Greater amounts of the acetals" can be used, even as high as 50 weight percent or higher, the upper limit being determined by their solubility and the desired add-on to the fabric. The add-on will usually vary from about 1 to weight percent, based on the weight of dry fabric. Below 1%, the glyoxal acetals produce little effect; and above 15%, they become uneconomical since little further improvement in properties is observed. Add-on of about 2-10 weight percent is the most practical and is preferred. The glyoxal acetals are conveniently applied to the fabric by passing the fabric through a padding bath, followed by a squeeze roller.

Whenthe glyoxal acetals are applied in a separate solvent step, the impregnated fabric is dried at about 25-150" C. The drying time can vary within a rather broad range, the time being longer at lower temperatures. Usually, the impregnated fabric will be dried for about 30 seconds to minutes. The specific temperature-time combination 'will be'chosen on the basis of such factors as the ease of evaporation. of the solvent, the economics of the drying step, and the heat sensitivity of the fabric.

In order to produce a durable press fabric from this glyoxal acetal-treated fabric having improved tensile properties and abrasion resistance, a conventional paddry-cure durable press treatment using an agent such as dimethyloldihydroxyethyleneurea can be used. A typical formulation is shown below.

A suitable formulation in 1,1,1-dichloroethane is exemplified below.

FORMULATION II Component: Weight percent Commercial, 45 weight percent aqueous solution of dimethyloldihydroxyethyleneurea 16.00

Catalyst 0.5-3 Fabric Softener Moropol polyethylene emulsion (Mortex Chemical Products, Inc.) 3.5

Aerosol OT-75 Wetting agent (dioctyl ester of sodium sulfosuccinic acid) (American Cyanamid Co.) 1.3 Glyoxal acetals 5 1,1,1-trichloroethane Balance The durable press agent usually is applied to give an add-on of from 5 to 15% based on the weight of the dried fabric. Below 5% little improvement in fabric properties is gained, and above 15% the treatment becomes economically unattractive. The catalyst add-on ranges from 0.5 to 3% based on the weight of the dry fabric.

Sutable catalysts include such Lewis acids as salts of Sn, Fe, Mg+ Fe+ Gu Ca+ Co+ Zn+ Ni+ Mn+ Sr, Cd, and Ba; the salt anions being, for example, B1 I-, BF, C10 1 Cl-,No or SO4 Mixtures of such Lewis acids with certain aliphatic carboxylic acids are particularly effective. Suitable aliphatic acids are mainly hydroxy and alkoxy acids such as hydroxyacetic, tartaric, citric, malic, lactic, 3-hydroxybutyric, and methoxyacetic acid. Mixed catalysts for cellulose crosslinking reactions discussed in a recent article by Pierce et al. in Am. Dyestuff Rep., May 1970, p. 50, are useful in the process of the present invention. In such mixtures, the relative proportions of the Lewis acid and of the aliphatic carboxylic acid can vary from about 5:1 to about 1:5 by weight. A Lewis acid is a substance which can accept electron pairs to form coordinate bonds.

The particularly preferred catalysts are zinc nitrate, zinc chloride, and mixtures of zinc nitrate or zinc chloride 'with hydroxyacetic acid.

The catalyst concentration can range from about 0.5 to 3 percent, based on the weight of the durable-press formulation; and the add-on of the catalyst to the fabric can range from about 0.5 to 3 percent, based on the weight of the dry fabric.

The treated fabric is dried and cured either immediately or after its fabrication into garments (post-cure). The drying temperature can range from about 25 to C., and the time can range from about 30 minutes to 5 minutes. The curing temperature varies from about to. 200 C. and the time from about 10 minutes to 2 minutes. Above a 90 C. drying temperature some curing begins to occur which interferes with the post-cure treatment, and below 25 C. the drying time becomes uneconomically long. However, when no post-cure is contemplated, the steps of drying and curing can be combined into one operation. Above 200 C. curing temperature, undesirable fabric deterioration begins to occur, and below 120 C. the curing reaction is uneconomically slow.

When the glyoxal acetals and durable press formulations are applied simultaneously in either an aqueous or solvent emulsion, the treated fabric can be dried and cured using the same times and temperatures.

The durable press properties of a fabric can be quantitatively expressed as the wrinkle recovery angle of such fabric. The wrinkle recovery angle is determined using the Recovery Angle Method (American Association of Textile Chemicals and Colorists, Test Method 66-1968). A total of 8 warp and 8 fill specimens are measured for each treatment. The reported wrinkle recovery angle (WRA) is the sum for the means for the 8 warp and 8 fill specimens. For a durable press fabric, an acceptable WRA value is about 280.

In evaluating other physical properties of the treated fabrics, standard test procedures are used.

The tear strength is determined by the falling pendulum method (Elmendorf) (ASTM Test Method D-1424-63) which measures the average force required to continue a tongue-type tear in a fabric through a fixed distance. A total of six warp and six fill specimens are measured for each treatment. The reported tear strength is the sum of the means for warp and fill specimens. Fabrics which halve good tensile properties show a high tear strength va ue.

The abrasion resistance as measured by Weight loss is determined using the Accelerotor Method (AATCC 93- 1966T), which subjects a test specimen to flexing, rubbing, shock, compression and stretching, while impinging it on the walls and abradant liner of the test chamber. Four cotton specimens are abraded for 3 minutes each, and four Dacron/cotton specimens are ab-raded for 5 minutes each at 3600 revolutions per minute with a No. 250 liner for each treatment, and the reported percent Weight loss is the mean for the four samples.

The invention is now illustrated by the following representative examples of certain preferred embodiments thereof, wherein all parts, proportions, and percentages are by weight unless indicated otherwise.

The following fabric samples were obtained from Testfabrics Inc., New York, N.Y.: (a) 65/35 poly(ethylene terephthalate) (Dacron) /cotton shirting 8/4706 and (b) 80 x 80 (threads per inch in warp and fill, respectively) cotton print cloth S/400WM.

- 7. A durable press cel1u1o sic fabric having improved OTHER R FERENCES tensile properties and abrasion resistance, said fabric 10 Chem Soc 7 1384 (1951), Sprung et being prepared by the process of claim 1. Ind. and Eng. Chem., 46, 787 (1954), Astle et a1.

References Cited 5 WILLIAM D. MARTIN, Primary Examiner UNITED STATES PATENTS T. G. DAVIS, Assistant Examiner 3,015,584 1/1962 Reinhardt et a1. 117- 139.4 Us. CL XR 2,731,364 1/1956 Reibnitz et a1. 117-139.4- X 117-139.4, 143 A 

